Latching apparatus for installing safety valves in wells

ABSTRACT

In accordance with an illustrative embodiment of the invention disclosed herein, an apparatus for releasably latching the lower end of a tubing string in a well casing having a landing nipple therein includes laterally flexible anchors carried by a body structure and held inwardly during running. When the anchors encounter the recesses in the nipple, they resile outwardly to stop downward movement, whereupon a clutch can be released to enable the body structure to be moved downwardly to releasably lock the anchors in set position. A seal on the body structure closes the tubing-to-casing annulus so that it can be used for a pressure path to a remote controlled safety valve installed in the tubing above the latching apparatus.

[451 Apr. 9, 1974 LATCHING APPARATUS FOR INSTALLING SAFETY VALVES INWELLS [75] Inventor: David E. Young, Friendswood, Tex.

[73] Assignee: Schlumberger Technology Corporation, New York, N.Y.

221 Filed: May 9,1973

21 Appl. No.2 358,772

[52] US. Cl. 166/136, 166/214 [51] Int. Cl E2lb 23/00, E2lb 33/12 [58]Field of Search 166/136-139, 166/213-217 [56] References Cited 7 UNITEDSTATES PATENTS 2,673,614 3 1954 Miller...- 166/136 3,279,542 10/1966Brown 166/139 3,292,717 12/1966 Hall et a1... 166/217 3,420,306 l/l969Brown 166/215 3,698,477 10/1972 Radig 166/214 Primary Examiner.lames A.Leppink Attorney, Agent, or FirmDavid L. Moseley; Stewart F. Moore;William R. Sherman 57 ABSTRACT In accordance with an illustrativeembodiment of the invention disclosed herein, an apparatus forreleasably latching the lower end of a tubing string in a well casinghaving a landing nipple therein includes laterally flexible anchorscarried by a body structure and held inwardly during running. When theanchors encounter the recesses in the nipple, they resile outwardly tostop downward movement, whereupon a clutch can be released to enable thebody structure to be moved downwardly to releasably lock the anchors inset position; A seal on the body structure closes the tubing-tocasingannulus so that it can be used for a pressure path to a remotecontrolled safety valve installed inthe tubing above the latchingapparatus.

11 Claims, 5 Drawing Figures LATCHING APPARATUS FOR INSTALLING SAFETYVALVES IN WELLS -,This invention relates generally to downhole safetyvalve installations, and more particularly to a new and improvedlatching assembly for anchoring the lower end of a production tubinghaving a remote controlled safety valve therein in a well casing.

Remote controlled safety valves are commonly used in producing wells asa means of providing downhole protection against disastrous surfacefires and blowouts caused by-failure, leakage or loss of surfaceequipment such as valves and flow lines. This type of safety valveisusually spring loaded to be normally closed, but is held open by thepressure of fluid in a control line extending to the surface. An absenceof control pressure in the line due to the sensing of actual orimpending surface disaster enables the valve to automatically close andshut-in the well downhole.

The remote controlled type of safety valve, while being preferred bymany well owners, requires the existence of a special landing sub in theproduction string. The sub normally has spaced apart seal surfaces witha lateral port therebetween that is coupled to the control lineextending externally of the production string in order to feed pressureto the valve which is installed inside the sub. Where such equipment hasnot been previously installedas a part of the well casing program, itbecomes quite expensive to make such an installation. Moreover, in theso-called tubingless completion wells, were a small diameter casing iscemented in the borehole and serves as the production string, it may notbe possible to install the landing sub and control line necessary forconvention remote control valve installation. However, it-has beentypical practice to install in most wells at least a landing nipple thatwill ac-' cept a so-called velocity sensitive safety valve. This type ofvalve is spring loaded to be normally open and incorporates a flowrestriction that creates a pressure drop, with the resultant forceovercoming the spring at a predetermined excessive flow rate and causingthe valve to close. Inasmuch as this type of valve is responsiveto'excessive flow rate, a separate control pressure line that extends tothe surface is not a requirement of the installation.

Moreover, the need for a separate control line itself has made theinstallation of remote controlled safety valve quite expensive comparedto other type valves, since the line must be run with the tubing. Thisrequires aconsiderable'amount of additional rig time and handlingexpense. 7 One object-of the present invention is to provide a new andimproved apparatusthat enables a remote controlled safety valve to bereadily installed in an existing well that does not have the previouslypositioned special equipment that is normally required for this type ofinstallation.

Another object of the present invention is to provide a new and improvedapparatus that enables the installation of a remote controlled safetyvalve in an existing well which eliminates the requirement for aseparate control line extending to the top of the well.

These and other objects are attained in accordance with the concepts ofthe present invention through the provision of a latching apparatus forattaching the lower end of the production string to a previouslyinstalled, conventional, velocity valve landing nipple in 2 such amannerthat the tubing-to-casing annulus can be used as a pressure pathto control the operation of a remote controlled safety valve located inthe tubing string thereabove. The apparatus, in a preferred form,comprises a body member or mandrel having its upper end adapted forconnection tothe pipe string, and a friction drag assembly carried byits lower end portion. The drag assembly has friction elements inengagement with the well casing wall, and is movable between a lowerposition and an upper position with respect to the mandrel. The assemblyis releasablycoupled to the mandrel in the lower position by amechanism'that can be released in response to rotation of the tubing. Ananchor sleeve is fixed to the upper end of the drag assembly and isprovided with laterally flexible spring fingers having head portionsthat normally are held inwardly alongside a reduceddiameter section themandrel as the apparatus is being run into the casing, however when thelanding sub is reached the head portions are sized and arranged to shiftoutwardly into a locking recess in the sub. When this occurs the tubingcan be. rotated to release the coupling to the drag assembly, and thenlowered to cause the head portions to be engaged by a locking surface onthe mandrel. Also, the head portions and mandrel have ratchet teeth thatengage to lock the mandrel in its lower position where a seal as-'sembly on the upper end portion thereof engages a surrounding sealsurface on the landing sub to prevent fluid leakage. Inasmuch as thetotal production flow must now pass through the mandrel and into thetubing, a remote controlled safety valve installed in the tubingthereabove can be-actuated because the tubing-tocasing annulus locatedabove the seal assembly may be employed as a means to provide control.pressure to hold the valve open. Thus the apparatus of this inventionenables this type of valve to-be installed in almost any existing well,and eliminates the need to have a separate control line that extends inthe annulus-to the surface.

Thepresent invention has other objects and advantages that will becomemorereadily apparent in connection with the following detaileddescription, taken in conjunction with the appended drawings in which:

FIG. 1 is a schematic representation of a cased well with a productionstring of tubing anchored therein in accordance with the principles ofthe present invention.

FIGS. 2A and 2B are longitudinal sectional views of the latchingapparatus with the parts in relative position for running into the well;and

FIGS. 3A and 3B are views similar to FIG. 2 except with parts inrelative positions when anchored and sealed off with respect to alanding nipple installed in the casing. v 7

Referring initially to FIG. 1, a downhole safety valve installation isshown somewhat schematically as including a string of production tubing10 located concentrically within a well casing 11. The well casing 11has a landing nipple 12 disposed therein, and the latching assembly 13in accordance with the concepts of the present invention is shown lockedinto the landing nipple. As will be described in greater detailherebelow, the latching assembly 13 includes a hollow mandrel 14 thatcarries anchors 15 to lock the assembly in place within the landingnipple 12, and seal packing 16 that prevents fluid leakage between themandrel and the casing to confine the total flow of production fluids tothe bore of the mandrel. A friction drag mechanism 17 together with aclutch l8 cooperates in enabling setting and release of the anchors inresponse to appropriate manipulation of the mandrel 14 by the tubingstring 10.

The production string 10 can have a landing nipple positioned thereinand adapted to receive a wireline settable and retrievable, remotecontrolled safety valve as will be familiar to those skilled in the art.As previously mentioned, this type of landing nipple has a port 21located between upper and lower internal seal surfaces via which controlpressure is communicated to the valve. For further detail of this typeof landing nipple and safety valve, reference may be had to p. 3501 ofthe 1972-1973 edition of the Composite Catalog of Oilfield Equipment andServices. Alternatively, a typically constructed remote controlledsubsurface safety valve can be joined in the tubing above the latchingassembly 13, and would have a pressure port in direct communication withthe annulus space between the tubing and the casing so that the valvecan be maintained in the open position by fluid pressure applied to theannulus. In either case, moreover, the sub or the valve may be connectedto the upper end of the man- ,drel 14 by a joint of tubing 22 or thelike. In the event of surface disaster where the applied pressure islost or dissipated, the valve is designed in a conventional manner toautomatically close and shut-in the well.

Turning now to FIGS. 2A and 2B for structural details of the latchingassembly 13, the mandrel 14 can be connected by threads 25 to the lowerend of the section of tubing 22 and has an outwardly directed shoulder26 above which is disposed the annular seal assembly 16. The sealassembly 16, which can take any suitable form, is shown as includingchevron packing elements 27 and 28 together with appropriate spacerrings 29-31. The upper end of the seal assembly 16 may be retained bythe lower end face 32 of the tubing section 22. When positioned withinthe landing nipple 12, the seal assembly 16 engages a surrounding sealsurface so that the total flow of production fluids is constrained topass through the central bore 33 of the mandrel 14. The lower end of themandrel 14 is connected by threads 34 to a bottom sub 35 (FIG. 2B)through which the production fluids enter.

The friction drag assembly 17 is carried intermediate the ends of themandrel l4 and includes a plurality of circumferentially spaced .bowsprings 38 or the like that extend outwardly into frictional engagementwith the inner wall surface of the casing 11 to prevent relativerotation. The ends of the bow springs 38 are retained by caps 39 and 40that are located near the respective ends of an annular cage 41 andfixed with respect thereto by threads 42 or the like. The caps are, ofcourse, arranged to provide for a certain amount of vertical movement ofthe ends of the bow springs to accomodate lateral flexure thereof. Thecage 41 has a counterbore 43 that provides an upwardly facing stopsurface 44 that is aligned for engagement by an outwardly directedshoulder 45 on the mandrel 14 to provide a stop limit to upward movementof the drag assembly with respect to the mandrel. However, as the deviceis being run into the well, the drag assembly 17 is held in a lowerposition with respect to the mandrel 14 by the clutch 18 that includesflexible fingers 46 depending from the lower cap 40 and having upwardlyfacing teeth 47 that are normally engaged with downwardly facing teeth48 on the lower sub 35. The teeth 47 and 48 preferably are formed onaright hand helix so that rotation of the mandrel 14 to the right willunthread the sub 35 from the fingers 46 and enable downward movement. Ofcourse the clutch 18 can be reengaged without rotation by simply movingthe mandrel 14 upwardly because the teeth 48 can ratchet back intoengagement with teeth 47 due to the capability of the fingers 46 toresile outwardly.

An anchor sleeve 50 is threaded at 51 to the upper end of the cage 41and is longitudinally cut by a plurality of slots 52 all extending fromthe upper end thereof for less than its full length in order to providea plurality of circumferentially spaced, flexible spring fingers 53.Each spring finger 53 has an enlarged head portion 54 at its upper endand an outwardly directed shoulder 55 intermediate its ends. The headportions 54 each have an upwardly and inwardly inclined upper surface 56and a transverse lower surface 57, together with internal buttress-typethreads 58 that face downwardly and are sized to mesh with externalthreads 59 on an enlarged section 60 of the mandrel 14 as will be morefully described herebelow. During running, the head portions 54 arelocated as shown in FIG. 2A adjacent to a reduced diameter portion 61 ofthe mandrel and are held in an inwardly flexed and inactive position bythe shoulder 55 whose outer surfaces 62 are adapted to slide in contactwith the inner wall of the casing 11. When the head portions 54 andshoulder 55 arrive at a landing nipple having complementary shapedinternal recesses, however, they are permitted to move outwardlyrelative to the mandrel 14 to a position where the transverse surfaces57 stop'downward movement. Moreover, when the clutch 18 is released aswill be subsequently explained, the enlargeddiameter section 60 of themandrel 14 can be positioned behind the head portions 54 in a mannersuch that a locking surface 64 will function to prevent inward movement.The external teeth 59 can be ratcheted into engagement with the internalteeth 58 to lock the mandrel 14 in a lower position within the landingnipple where'the seal assembly 16 engages a surrounding seal surfacetherein.

In operation, the parts are assembled as shown in the drawings and runinto the casing l 1 with the threads 47 and 48 on the clutch sleeve'46and the bottom sub 35, respectively, engaged to position the anchorassembly 15 and the drag assembly 17 in a lower position along themandrel 14. The shoulder 55 engage in inner wall of the casing. 11 asshown in dotted lines in FIG. 2A, causing the fingers 53 to resileinwardly and thereby positioning the head portions 54 alongside thereduced diameter section 61 of the mandrel. When the latching assemblyarrives at the seating nipple 12 as shown in FIG. 3A, which containsspaced apart internal recesses and 71 that are companion in shape andspacing to the outline of the head portions 54 and the shoulders ,55,the shoulders enter the lower recess 71 and enable surface 73. Then themandrel 14 is rotated by the tubing 10 to the right, resulting inrelease of the clutch threads 47 and 48 since the cage 41 is heldagainst rotation by the drag springs38. When the threads 47 and 48 arereleased, the mandrel 14 can be telescoped the lower end of the tubingis firmly anchored and sealed within the landing nipple 12. Moreover,the annular space 75 between the casing 11 and the tubing 10 provides apressure path from the surface to the remote controlled safety .valvepositioned within the nipple 20.

above the latching assembly 13.

To'release the tubing 10 so that the latching assembly.

13 and equipment thereabove can be withdrawn from the well, it isonly'necessary to rotate the mandrel 14 to the right while holding astrain in the tubing. This causes the threads 58 and 59, which arepreferably of left hand formation, to disengage and enables the lockingsurface 63 to be removed from behind the head portions 54 as the mandrel14 shifts upwardly. At the limit of its upward relative movement, theclutch 18 will automatically engage as the sub teeth 48 ratchet backinto engagement with the teeth 48 on the clutch sleeve 46. As the dragassembly 17 and the anchor sleeve 50 are forced upwardly, the springfingers 53 are flexed inwardly to a disarmed position due to cammingaction of the inclined surfaces 56 and 74, and are held in such positionby the shoulders 55 which disengage from the recess 71 and slide alongthe inner wall of the casing 11. The tubing can be removed fromthe'well, or for that matter the assembly '13 can be set and released asmany times as desired to facilitate spacing procedures at the surfacethat are sometimes necessary when installing surface productionfacilities.

. It will now be recognized that a new and improved latching assemblyhas been provided that enables the installation of remotely controlledsubsurface safety valve equipment in existing wells. Moreover, thetubing-to-casing annulus can be utilized asa pressure path for controlpressure to actuate such valves, eliminating the need for runningseparate control pressure lines externally of the production tubing.Since certain changes or modifications may be made in the disclosedembodiment bythose skilled in the art without departing from the scopeof the inventive concepts disclosed herein, it is the aim of theappended claims to cover all such changes or modifications fallingwithin thetrue spirit and scope of the present invention.

1 claim:

1. Apparatus for use in anchoring in a well casing having a landingnipple provided therein, said'landing nipple having internal recessmeans, comprising: 'a body structure having an enlarged diameter sectionand a reduced diameter section; seal means on said body structurearranged to engage acompanion seal surface on said landing nipple forpreventing fluid leakage; anchor means movable relatively along saidbody structure'and between an inner position adjacent said reduceddiameter section and an outer position, said anchor means includingsurface means adapted to slide against the casing and hold said anchormeans in said inner position, said surface means when encountering saidrecess means enabling outward movement of said anchoringmeans thereinto;clutch r'neansresporis'ive to manipulation of said body structure forselectively preventing or permitting longitudinal movement of saidanchor means relatively along said body structure; and means provided onsaid enlarged diameter section of said body structure that can bepositioned by longitudinal relative movement for locking said anchoringmeans in said outer position to anchor said production string in thewell casing.

2. The apparatus of claim 1 wherein said anchor means includes aplurality of circumferentially spaced, flexible spring fingers eachhaving an enlarged head portion shaped to cooperate with said recessmeans to prevent longitudinal movement when engaged therein.

3. The apparatus of claim 2 wherein said surface means is provided onthe periphery of an outwardly directed shoulder on each of said springfingers, said recess means being shaped and arranged to receive saidshoulders and thereby enable outwardmovement.

4. The apparatus of claim 2 wherein said head portions and said enlargeddiameter section of said body structure have releasable, coengageablemeans for preventing upward movement of said body tive to said headportions.

5. The apparatus of claim I wherein said clutch means comprises acoupling between said anchor means and said body structure'that can bereleased by movement of said body structure'with respect thereto; andfurther including means attached to said anchor means and frictionallyengageable with the well casing for enabling movement of said bodystructure with respect to said anchor means. v

6. Apparatus for use in releasably securing a remote controlled safetyvalve attached in a production string within a well casing in such amanner that the annular space between the production string and thecasing provides a means of communicating operating pressure to thesafety valve, said casing having a landing nipple with vertically spacedrecesses therein and an annular internal seal surface, comprising: abody structure having a through bore and carrying means engageable withsaid seal surface to confine a flow of production fluids to said throughbore; anchor means on said body structure movable laterally with respectthereto between an inner inactive position and an outer active positionin engagement .with one of said recesses; means engageable with thecasing for holding said anchor means in said inactive position as saidapparatus is being moved through the well bore, said holding means beingreceived by the other of said recesses to enable outward movement ofsaid anchoring means to said active position; means responsive tolongitudinal movement of said body member relative to said anchor meansfor locking said anchor means in said active position; and selectivelyoperable means responsive to manipulation of said body member by theproduction string for either preventing or permitting such longitudinalmovement;

structure relacess, and when received therein to prevent longitudinalmovement.

8. The apparatus of claim 7 wherein said locking means includes anenlarged diameter section of said body member having a locking surfacethat when located behind said head portions prevents inward movementthereof.

9. The apparatus of claim 8 further including coengageable means on saidenlarged section and the inner surfaces of said head portions forpreventing upward movement of said body member with respect thereto.

10. The apparatus of claim 7 wherein said holding means includesoutwardly directed shoulder formations on each of said spring fingers,each shoulder formation providing an outer surface that slides incontact with the well casing wall to hold each head portion in saidinactive position, said shoulder formations entering said other of saidrecesses to enable outward movement of said head portions to said activeposition.

1 l. The apparatus of claim 7 wherein said selectively operable meanscomprises a threaded coupling between said sleeve member and said bodymember for normally preventing relative movement, said coupling beingreleasable by relative rotation; and further including friction dragmeans connected to said sleeve member for enabling such relativerotation.

1. Apparatus for use in anchoring in a well casing having a landingnipple provided therein, said landing nipple having internal recessmeans, comprising: a body structure having an enlarged diameter sectionand a reduced diameter section; seal means on said body structurearranged to engage a companion seal surface on said landing nipple forpreventing fluid leakage; anchor means movable relatively along saidbody structure and between an inner position adjacent said reduceddiameter section and an outer position, said anchor means includingsurface means adapted to slide against the casing and hold said anchormeans in said inner position, said surface means when encountering saidrecess means enabling outward movement of said anchoring meansthereinto; clutch means responsive to manipulation of said bodystructure for selectively preventing or permitting longitudinal movementof said anchor means relatively along said body structure; and meansprovided on said enlarged diameter section of said body structure thatcan be positioned by longitudinal relative movement for locking saidanchoring means in said outer position to anchor said production stringin the well casing.
 2. The apparatus of claim 1 wherein said anchormeans includes a plurality of circumferentially spaced, flexible springfingers each having an enlarged head portion shaped to cooperate withsaid recess means to prevent longitudinal movement when engaged therein.3. The apparatus of claim 2 wherein said surface means is provided onthe periphery of an outwardly directed shoulder on each of said springfingers, said recess means being shaped and arranged to receive saidshoulders and thereby enable outward movement.
 4. The apparatus of claim2 wherein said head portions and said enlarged diameter section of saidbody structure have releasable, coengageable meAns for preventing upwardmovement of said body structure relative to said head portions.
 5. Theapparatus of claim 1 wherein said clutch means comprises a couplingbetween said anchor means and said body structure that can be releasedby movement of said body structure with respect thereto; and furtherincluding means attached to said anchor means and frictionallyengageable with the well casing for enabling movement of said bodystructure with respect to said anchor means.
 6. Apparatus for use inreleasably securing a remote controlled safety valve attached in aproduction string within a well casing in such a manner that the annularspace between the production string and the casing provides a means ofcommunicating operating pressure to the safety valve, said casing havinga landing nipple with vertically spaced recesses therein and an annularinternal seal surface, comprising: a body structure having a throughbore and carrying means engageable with said seal surface to confine aflow of production fluids to said through bore; anchor means on saidbody structure movable laterally with respect thereto between an innerinactive position and an outer active position in engagement with one ofsaid recesses; means engageable with the casing for holding said anchormeans in said inactive position as said apparatus is being moved throughthe well bore, said holding means being received by the other of saidrecesses to enable outward movement of said anchoring means to saidactive position; means responsive to longitudinal movement of said bodymember relative to said anchor means for locking said anchor means insaid active position; and selectively operable means responsive tomanipulation of said body member by the production string for eitherpreventing or permitting such longitudinal movement.
 7. The apparatus ofclaim 6 wherein said anchor means comprises an elongated sleeve membersurrounding said body member and being longitudinally slotted from oneend thereof for less than its full length to provide a plurality ofcircumferentially spaced, flexible spring fingers, each spring fingerhaving a head portion shaped and arranged to be received by said onerecess, and when received therein to prevent longitudinal movement. 8.The apparatus of claim 7 wherein said locking means includes an enlargeddiameter section of said body member having a locking surface that whenlocated behind said head portions prevents inward movement thereof. 9.The apparatus of claim 8 further including coengageable means on saidenlarged section and the inner surfaces of said head portions forpreventing upward movement of said body member with respect thereto. 10.The apparatus of claim 7 wherein said holding means includes outwardlydirected shoulder formations on each of said spring fingers, eachshoulder formation providing an outer surface that slides in contactwith the well casing wall to hold each head portion in said inactiveposition, said shoulder formations entering said other of said recessesto enable outward movement of said head portions to said activeposition.
 11. The apparatus of claim 7 wherein said selectively operablemeans comprises a threaded coupling between said sleeve member and saidbody member for normally preventing relative movement, said couplingbeing releasable by relative rotation; and further including frictiondrag means connected to said sleeve member for enabling such relativerotation.